This invention relates to a method for removing oxygen from oxygen-containing compounds such as, for example, lignin, cellulose and coals such as bituminous coal, sub-bituminous coal, brown coal, lignite and grass peat and consequently producing from said compounds low molecular organic substances.
The high-pressure hydrogenation process which effects deoxidation by use of hydrogen has heretofore been available for removal of oxygen from oxygen-containing compounds. This technique is connected with liquefaction of coal.
In view of the present worldwide energy crisis, there is an acute need for inexpensive and effective techniques for the conversion of coals to a clean, liquid energy source, namely, for the production of man-made petroleum.
The high-pressure hydrogenation process for deoxidization by use of hydrogen is one of the techniques which have been developed to answer the need.
Coals have low hydrogen content as compared with liquid petroleum. Liquefaction of coals, therefore, is accomplished by hydrogenating coals at elevated temperatures under high pressure. At the same time, the oxygen contained in coals in amounts ranging from several percent to several tens of percent is caused to react with the hydrogen and is consequently removed in the form of water. This technique, thus, requires hydrogen for the removal of oxygen and for increasing the hydrogen content in the whole composition.
The production cost of hydrogen if fairly high at present. Brown coal, lignite, etc. occur abundantly throughout the world. They are inexpensive and generally possess high capacity for decomposition by hydrogenation. Notwithstanding such advantageous factors, they are not valued highly as the raw material for liquefaction of coal. This is because they have high oxygen content which can now be removed only through the consumption of a large amount of hydrogen, a factor which renders the operation economically infeasible.
An object of the present invention is to provide a method for easily removing oxygen from such oxygen-containing compounds as coals, lignin and cellulose which are natural resources available in immense abundance.
Another object of the present invention is to provide a method for producing low molecular compounds from coals, lignin, cellulose, etc.